Cranes occupy a crucial role within industry. They are used throughout the world in thousands of shipping yards, construction sites, steel mills, warehouses, nuclear power and waste storage facilities, and other industrial complexes. The significant role that these systems maintain in the world can hardly be overestimated.
Cranes are highly flexible in nature, generally responding in an oscillatory manner to external disturbances and motion of the overhead support unit (e.g., the bridge or trolley). In many applications this oscillation has adverse consequences. Swinging of the payload or hook makes precision positioning time consuming and inefficient for an operator. This condition is exacerbated in double-pendulum cranes where the payload motion is a combination of oscillations at two different frequencies. The oscillations of the payload and/or hook can present control problems for operators and safety hazards to both personnel and equipment.